Multiple orifice rotary control valve

ABSTRACT

A rotary control valve having a control member provided with a plurality of circumferentially spaced, fixed area orifices having their axes disposed at an angle to the axis of rotation for selective registry with a flowway through the valve disposed at the same angle to the axis of rotation, whereby to provide straight-line flow through the valve at all orifice settings.

United States Patent [72] Inventor Eldon E. Hulsey 717,688 l/1903 Kems 251/207X 5747 Warm Springs, Houston, Tex. 77035 9 /19 0 M d /2 [21] Appl. No. 699,947 3,080,146 3/1963 Lombardi.. 251/310 [22] Filed Jan. 23,1968 1,043,935 11/1912 Hitchcock 251/209X [45] Patented Jan. 26, 1971 1,314,003 8/1919 Leese 251/207X Continuation-impart of application Ser. No. 3,241,570 3/1966 Mueller 25 1/3 12X 604,414, Dec. 23, 1966, now Patent No. FOREIGN PATENTS May 44,575 9/1888 Germany 251/209 1 Primary Examiner-Henry T. Klinksiek [54] MULTIPLE ORIFICE ROTARY CONTROL VALVE Attorney-R. Werlin 14 Claims, 6 Drawing Figs.

[52] US. Cl 251/207, 251/209 [5 A rotary control valve having a control member [50] Field of Search 251 /205- provided with a plurality f i f i ll Spaced, fi d 3O93 12 area orifices having their axes disposed at an angle to the axis of rotation for selective registry with a flowway through the [56] References Cited valve disposed at the same angle to the axis of rotation, UNITED STATES PATENTS whereby to provide straight-line flow through the valve at all 667,891 2/ 1901 Neudecker 251/207X orifice settings.

1 f l 1 I 6'7 L J I f I 72 l I I 5g 1 1 l I L a I 8 l- 8/ 90 I 80 i i as -14 a0 PATENTEUJMB ISYI I SHEET 1 BF 2 5/0 00 E. //U/Jey INVIiN'lUR.

ATTORNEY PATENTED JAN26 1971 SHEET 2 0F 2 4 /0 00 Hu/Jey INVIZN'IUR.

ATTORNEY MULTIPLE ORIFICE ROTARY CONTROL VALVE This application is a continuation-in-part of my copending application, Ser. No. 604,414, filed Dec. 23, I966 now US. Pat. No. 3,443,793, issued May I3, 1969 for VARIABLE AREA ORIFICE, ROTARY CONTROL VALVE.

In the aforesaid copending application, Ser. No. 604,414, I have disclosed a form of rotary control valve which comprises a casing defining a closure-receiving chamber having spaced openings in the casing communicating with the chamber to define a flowway therethrough disposed at an acute angle to a main axis of the chamber, a closure member rotatably disposed in said chamber and comprising a body shaped to fit the chamber and having an axis of rotation coaxial with said chamber axis, and a flow passage extending the through the closure body at said acute angle with respect to said axis of rotation, whereby to be in register with said openings at the position of the closure member.

The aforesaid control valve is further defined in that the flow passage through the closure member is defined at one or both ends by an elongate slot extending circumferentially of the body and defined by convergent walls which are inclined so as to intersect the flow passage through the closure member at an acute angle to the axis of the passage. The slot or slots, soshaped and inclined, are designed when rotated to cooperate with the angularly disposed flowway to vary the effective are cross-sectional area of the flowway in accordance with the angular position of the slotted ends of the flow passage relative to the flowway openings while maintaining substantially straight line or through-conduit flow through the flowway at all valve-open positions. 7

The present application discloses valve constructions embodying the novel structural features disclosed in the aforementioned application including a modification of one of the principal embodiments of the earlier application, as well as a new multiple orifice construction.

In a principal embodiment of the earlier application, the closure member was in the form of a substantially solid body through which a flow passage was formed having the disclosed novel configuration. In one embodiment in accordance with the present invention, to be described in detail hereinafter, the closure member is in the form of a tubular sleeve or body having a flow passage therethrough possessing the same characterizing features of the corresponding embodiment of the earlier application. By employing a sleeve-type body rather than a substantially solid body, it is found that manufacture of the valve is greatly simplified, the weight and cost correspondingly reduced, and the cost of replacement of the closure member, when required, is greatly reduced, without sacrifice of the novel flow characteristics of the valve.

The multiple orifice embodiment of a rotary control valve in accordance with the present invention, likewise employs a tubular or sleeve-type body as the control member which is mounted in the valve body for rotation about an axis which is mounted in the valve body for rotation about an axis which is disposed at an acute angle to the axis'of the flowway through the valve. However, instead of elongate slots, the present embodiment employs a plurality of fixed area orifices, which may be of the same or differing cross-sectional areas, disposed in circumferentially spaced relation about the control body, all of the orifices being disposed generally in a plane normal to the longitudinal axis of the body of the control member and in termediate the ends of the body. Each of the orifices extend through the wall of the body at an angle such that its axis will coincide with the axis of the flowway through the valve when the orifice is rotated into registry with the flowway. With this arrangement, fluid flow through each orifice will be straightflow, thereby eliminating changes in direction and obviating the erosion and abrasion which occur in more conventional designs of multiple orifice, or so-called variable choke valves, particularly under the high pressure, high velocity flow conditions to which such control devices are commonly subjected.

Another advantageous feature of the present invention is the use with the sleeve-type control member of separable end members carrying trunnions by means of which the opposite ends of the control member may be rotatably journaled in the valve casing in a manner to effectively balance the control member, enabling greater ease of operation and reduction in operating torque requirements.

Other and more specific objects and advantages of this invention will become more readily apparent from the following detailed description when read in conjunction with the accompanying drawing which illustrates useful embodiments in accordance with this invention.

In the Drawing:

FIG. 1 is a longitudinal, partly sectional view of a control valve in accordance with one embodiment of the present invention, the valve being shown in the closed position;

FIG. 2 is an exploded view, partly in section, of the closure member employed in the valve illustrated in FIG. 1, the closure member being shown rotated at an angle of from that shown in FIG. 1;

FIG. 3 is a longitudinal, sectional view of a multiple orifice control valve in accordance with another embodiment of the invention;

FIG. 4 is a cross-sectional view taken along line 44 of FIG.

FIG. 5 is an elevational view in perspective of the control member employed in the embodiment illustrated in FIG. 3; and

FIG. 6 is a perspective view of a detail of the valve structure.

Referring first of FIGS. I and 2, the valve includes a casing 10 having a generally cylindrical bore defining a closurereceiving chamber 11. The ends of casing 10 are closed by means of bonnet members 12 and 12a removably secured thereto in any conventional manner (not shown). Chamber 22 11 is adapted to receive a closure member, designated generally by the numeral 13, and comprising a tubular sleeve 14, having an axial bore 15, snugly fitting the bore wall of chamber 11 and disposed for rotation therein, the wall forming a seat for the closure member.

The opposite ends of sleeve 14 are closed by removable end plugs 16 and 17 having external diameters to be flush with the exterior of sleeve 14 and having reduced diameter cylindrical extensions 18 and I9, respectively, dimensioned to have a snug sliding fit in bore 15 of the closure sleeve, and defining the inwardly facing annular shoulders 20 and 21, respectively, adapted to abut the adjacent ends of the closure sleeve. With the end plugs in place, the overall length of closure member 13 will be made such as to fit snugly between the opposed inner faces of bonnet members 12 and 12a.

End plugs 16 and 17 are provided with oppositely extending cylindrical stems or trunnions 22 and 23, respectively, of identical cross section, coaxial with'each other and with the longitudinal axis of sleeve 14. Trunnions 22 and 23 are journaled in coaxial openings 25 and 26 of the respective bonnet members 12 and 12a. Seal packings 27 and 2711 are mounted in openings 25 and 26, respectively, to seal about the respective trunnions.

One of the end plugs, plug 16 for example, may be constituted the drive member for rotating closure member 13, and to this end may be provided with one or more dowel pins or keys 30 (FIG. 2) projecting from shoulder 20 alongside extension 18 for reception in matching slots 31 provided the adjacent end of closure sleeve 14. Trunnion 22 functions as a drive stem and is separably connected to plug 16 by means of a connection including a socket 32 in the outer end of plug 16 into which the inner end of stem 22 slidably extends. Dowel pins 33 project upwardly from the bottom of socket 32 and are disposed for sliding reception in matching grooves or slots 34 in the inner end of stem 22, whereby to lock the stem against rotation relative to the plug. Spaced from its inner end, stem 22 carries an annular flange 35 which fits into a counterbore 36 in the outer end face of plug 16 to be flush therewith. With the bonnet member in place about the stem, flange 35 functions to prevent the stem from pulling out of the valve casing while permitting free rotation of the stem in opening 25. The

outer end of stem 22 carries means, such as the flats 37. for connection to the stem of any conventional type ofoperator to be employed for rotating the closure member.

Plug 17, while it may be ofidentical construction to plug 16, is illustrated in a form in which trunnion 23 is made integral with the plug. By providing the closure sleeve with the separable end plugs, it will be seen that replacement of the closure sleeve is greatly simplified and the cost reduced.

Casing is provided with registering openings 40-40 spaced 180 apart and disposed on an axis extending at an acute angle to the longitudinal axis of casing 10. Openings 40-40 define the inlet and outlet flow ports for the valve to which are connected the coaxial nozzles 41-41 defining the flowway through the valve by means of which the valve may be connected into a flow conduit to be controlled by the valve. As so arranged the valve is of the so-called angle" type, in that the main axis of the valve casing is disposed at an acute angle with respect to the longitudinal axis of the flow conduit in which it is mounted.

Closure member 13 is, as previously noted, of cylindrical, tubular shape and, as indicated in FIG. 2, has a flow passage 42 extending along an axis b-b at an acute angle x, with respect to the longitudinal axis of the closure member, indicated by the line a-a, so as to be coincident with the axis of the flowway through the valve when the closure member is in the valve-closing position. The opposite ends of the flow passage through the closure member are defined by orifice slots 43-43 of identical, generally convergent shape, but oppositely oriented, as will appear subsequently.

Slots 43 extend generally circumferentially of the closure member and are defined by convergent walls 44-45 which are inclined inwardly of the body of the closure member, so as to intersect the flow passage at an acute angle y, which is preferably equal to, but opposite, angle x of the flow passage, as indicated by the line c-c indicating the angle of inclination of walls 44 and 45. In development, slots 43 will have an elongate, generally triangular configuration with arcuate bases and will be oriented to extend in opposite directions about the clo sure body and to be angularly offset, as illustrated in FIGS. 1 and 2. The nonslotted portions of the body between the opposite ends of slots 43 define closure portions 46 adapted to register with the related flow ports 40 in the flowway-closing position of the closure member, as seen in FIGS. 1 and 2. Closure portions 46 may be enclosed by seal rings 47, such as conventional O-rings, seated in elliptically shaped grooves 48 to form fluid-tight seals around each of the flow ports 40 when the closure member is in the flowway-closing position (FIG. 1). An annular seal ring 49 is seated in a suitable groove 50 extending circumferentially about the closure member at its midpoint, whereby to seal ofi" the chamber 11 between the inlet and outlet ends thereof.

In general, the arcuate length of each slot 43 will be greater than 90 and preferably from about 180 to 270. This extended length of the slot will permit rotation of the closure member through an angle up to 270 between its fully closed and fully opened positions, thereby providing an extends extended range of variation in the orifice area for accurately controlling the flow of fluid through the valve.

By the described inclination of the walls defining slots 43 to the longitudinal axis of the closure member and to the axis of the flowway, it is found that at any open position of the closure member throughout the angular length of the slots, the flow path through the valve will be substantially coaxial with the flowway through the valve, thus providing straight line flow through the valve at any opening.

Angles x and y are, as previously note, acute angles and preferably will be in the range from about 30 to slightly less than 45 45, depending on the size of the valve; that is, the diameter of the flowway through the valve. In general, the larger the flowway diameter, the larger the angle. For example, in a nominal 2 inch valve, angles x and y will be approximately 37, while in a nominal inch valve, these angles will be approximately 45.

With the balanced symmetrical construction heretofore described, not only will the flow passage be straight line or through-conduit flow at all valve open positions of the closure member, but by reason of the identical configuration and dimensions of both, the inlet and outlet orifice slots and their reversed relationship with respect to one another, the orifice areas. both at the inlet and outlet ends of theflow passage, will be identical at all open positions, with the result that there'will be substantially no pressure drop across the valve. The straight line character of the flow will, of course, reduce turbulence to a minimum at any opening. This is a highly desirable and important characteristic in a control valve, since it eliminates many of the problems encountered in many conventional types of control valves.

Referring now to FIGS. 3 to 6, inclusive, which illustrate the multiple orifice embodiment in accordance with this invention, there is shown a valve casing 60 having a cylindrical bore 61 defining a seat for a tubular control member 62 mounted for rotation in chamber 61. The lower end of casing 60 is closed by an end wall 63 through which is formed an inlet opening 64 coaxial with an outlet opening 65 provided through the sidewall of casing 60 at a point such that the axis of the flowway defined by openings 64 and 65 will be disposed at an acute angle with respect to the main longitudinal axis of chamber 61 and control member 62, as indicated by the intersecting lines a and b in FIG. 3. Tubular nozzles 66 and 67 are connected into communication with openings 64 and 65 to define the flowway through the valve and for connection into a pipe line to be controlled by the valve. Control member 62 is, as previously noted, constructed in a form of a cylindrical sleeve, having an axial bore 68 and disposed in chamber 61 with its lower end seated against the inner face of bottom wall 63. An end plug 69, generally similar toend plug 16 of the previously described embodiment, is removably connected to the upper end of sleeve 62 by means of dowel pins 70, as in the previously described embodiment, and an operating stem 71 is likewise separably secured to the plug by means of dowel pins 72. Stem 71 extends through an opening 73 in a bonnet member 74 which closes the upper end of casing 60, being removably secured thereto by cap screws 75. Stem 71 is journaled in openings 73 coaxially with respect to control member 62 and spaced apart seal packings 76-76 are disposed in opening 73 about the stem. A channel 77 may be drilled laterally through bonnet member 74 to communicate with opening 73 between packing 76, and may be employed for injecting grease or other lubricant through a fitting 78, if desired or necessary to prevent fluid leakage past stem 71.

The wall of control member 62 is provided with a plurality of openings, each designated by the numeral 80, which may be of the same or different cross-sectional areas and which are arranged in angularly spaced relationship on a common plane normal to the axis of control member 62 intermediate the ends thereof. The axis of each of the openings or orifices 80 is inclined at an acute angle to the longitudinal axis of control member 62, which is, of course, the axis of rotation of the latter, the angle being the same as the angle between axes d and b, as seen in FIG. 3. Thus, when any of the orifices is rotated to a position coaxial with axis a of the flowway, the flow path for fluid passing through the valve will be along a straight line path coincident with the axis of the flowway, the flow directions being indicated by the arrows in FIG. 3. The control member will be provided with at least one blank portion, indicated at 82, designed to provide a flowway-closing portion of the control member.

Since the several orifices will usually be considerably smaller in area than inlet opening 64, outlet opening 65 may be fitted with an adapter having an axial bore 86 whose cross-sectional area will be substantially equal to the crosssectional area of the largest of the several orifices 80. Adapter 85 will normally be in a form of a short cylinder which can be inserted into the inner end of nozzle 67 from chamber 61 and seated in the nozzle against a shoulder 88 to prevent its being expelled from nozzle 67 by the force of fluid flowing through the valve. The inner end of adapter 68 is cut at an angle and arcuately curved to provide a surface 89 which will be flush with the inner surface of bore 61 and effectively constitute a portion of the seat for control member 62. Adapter 85 may be provided with an annular seal packing 90 to seal off between the adapter and the wall of nozzle 67.

Each of the orifices 80, as well as imperforate closure portion 82, will be enclosed by an annular seal packing 8t seated in the exterior of control member 62. Because of the angular disposition of the orifices, their inlet and outlet ends will take the general form of ellipses, as will the surrounding seal packings. Each of the latter will be dimensioned to form a seal about its respective orifice with the inner end face 89 of the adapter when the orifice is aligned with bore 86 of the adapter. I

With the above-described arrangement, as each orifice is disposed on the flow axis, it will define a portion of a flow path which, in each instance, will be straight line and reduce the possibility of abrasion and erosion by fluid flowing through the restricted area defined by the several orifices.

As noted, orifices 80 may all be of the same cross-sectional area or each may be of a different area. Also, the invention contemplates that there may be several groups of orifices, the orifices in each group being of equal dimension, but differing from the orifices of another group. Thus, anycombination of orifices may be employed as may be desired. Also, as noted, one or more spaces may be left imperforate to permit the control member to operate as a closure member for the flowway through the valve. 1

With a valve constructed as described, a very simple form of variable choke is provided which is readily adaptable for all types of fluid flow systems. The control member may be readily replaced, since it constitutes only a simple sleeve, whenever conditions of wear require a change to be made, although the degree of wear to which the closure member herein described may be subjected is considerably less than in other types of chokes. Suitable and well-known indexing devices may be provided between stem 71 and bonnet 74, or other parts of the valve, to permit alignment of selected orifices or closure portions with the outlet of the flowway, in accordance with the angular movement of the stem.

I claim:

1. A rotary valve comprising:

a. a casing defining a chamber having a main axis for receiving a flow-control member and having openings communicating with said chamber at spaced points to define a flowway therethrough on an axis disposed at an acute angle to said main axis of said chamber; and

b. a flow-control member rotatably disposed in said chamber comprising:

i. a tubular body shaped to fit said chamber and having an axis of rotation coaxial with said chamber axis;

ii. a flow passage extending through opposite walls of said body generally at said acute angle with respect to said axis of rotation whereby to be in register with said openings at the flowway-open position of said flowcontrol members; and

iii. cylindrical trunnion members carried by the opposite ends of said body and joumaled in said casing,

iv. each end of said flow passage being defined by an elongate slot in said body extending circumferentially of said body and defined by convergent walls inclined inwardly of said body to intersect said flow passage parallel to the flow axis thereof.

2. A rotary valve according to claim 1 wherein said flowcontrol member includes:

a. plug members removably closing the opposite ends of said flow-control member and carrying said trunnion members; i

b. at least one of said trunnion members being constructed to function as an operating stem for said flow-control member.

3. A rotary valve according to claim 1 wherein said slot has an arcuate length from about 90 to about 270.

4. For use in a rotary valve including a casing defining a closure-receiving chamber having a main axis and having openings communicating with said chamber at spaced points to define a flowway therethrough disposed at an acute angle to said main axis, a closure member comprising:

a. a body shaped to fit said chamber and having an axis of rotation coaxial with said chamber axis;

b. a flow passage extending through opposite walls of said body generally at said acute angle with respect to said axis of rotation whereby to be in register with said openings at the full flowway-open position of said closure e member;

c. each end of said passage defining an elongate slot extending circumferentially of said body and defined by convergent walls inclined inwardly of said body to intersect said passage parallel to the flow ax'is'of said passage;

d. said body having a non-slotted portion between the opposite ends of said slot defining a closure portion adapted to close off a flowway opening in the flowway-closing position of the closure member; and

e. means carried by the ends of said body for journaling said body in said casing.

5. A rotary valve, comprising:

a. a casing defining a chamber having a main axis for receiving a flow-control member and having openings communicating with said chamber at spaced points to define a flowway therethrough on an axis disposed at an acute angle to said main axis of said chamber; and

b. a flow-control member rotatably disposed in said chamber comprising:

i. a tubular body shaped to fit said chamber and having an axis of rotation coaxial with said chamber axis and having one end in open communication with one of said openings;

ii. a plurality of circumferentially spaced orifices extend ing through the wall of said body disposed generally in a plane normal to said axis of rotation and intermediate the ends of said body, each of said orifices having its axis at said acute angle whereby to be coaxial with said flowway when rotated into register with the other of said openings;

c. means connected to said body and joumaled in said casing for rotating said flow-control member;

d. a cylindrical operating stem extending to the exterior of said casing; and

e. a plug member carried by the inner end of said operating stem removably closing the adjacent end of said tubular body and secured thereto against relative rotation.

6. A rotary valve according to claim 5 having annular seal means disposed to seal between said body and said casing about said other of said openings.

7, A rotary valve according to claim 5 wherein an annular seal packing surrounds each of said orifices for sealing between said body and said casing about said other of said openings.

8. A rotary valve according to claim 5 wherein at least some of said orifices difier in cross-sectional area from others of said orifices.

9. A rotary valve according to claim 5 wherein said body has at least one imperforate portion between said orifices adapted when in registry with said other of said openings to close off said flowway.

10. A rotary valve according to claim 5 wherein the bore of said other one of said openings has a cross-sectional area substantially equal to that of the largest of said orifices and less than that of said one opening.

11. A rotary valve according to claim 5 including a tubular adapter removably positioned in the other of said openings, the inner end of said adapter being shaped to effectively form a flush portion of the interior wall of said chamber, said adapter having an axial passage therethrough whose cross-sectional area is substantially equal to that of the largest of said orifices.

12. A rotary valve according to claim 5 wherein said casing has an end wall closing one end of 'saidchamber and through least in part by convergent walls inclined inwardly of said body to intersect said passage parallel to the flow axis thereof;

d. said body having an a nonslotted portion between the opposite ends of said slot defining a closure portion; and

e. means carried by the ends of said body for supporting the same for rotation about said central axis.

14. A closure member according to claim 13 wherein said body is tubular. 

1. A rotary valve comprising: a. a casing defining a chamber having a main axis for receiving a flow-control member and having openings communicating with said chamber at spaced points to define a flowway therethrough on an axis disposed at an acute angle to said main axis of said chamber; and b. a flow-control member rotatably disposed in said chamber comprising: i. a tubular body shaped to fit said chamber and having an axis of rotation coaxial with said chamber axis; ii. a flow passage extending through opposite walls of said body generally at said acute angle with respect to said axis of rotation whereby to be in register with said openings at the flowway-open position of said flow-control members; and iii. cylindrical trunnion members carried by the opposite ends of said body and journaled in said casing, iv. each end of said flow passage being defined by an elongate slot in said body extending circumferentially of said body and defined by convergent walls inclined inwardly of said body to intersect said flow passage parallel to the flow axis thereof.
 2. A rotary valve according to claim 1 wherein said flow-control member includes: a. plug members removably closing the opposite ends of said flow-control member and carrying said trunnion members; b. at least one of said trunnion members being constructed to function as an operating stem for said flow-control member.
 3. A rotary valve according to claim 1 wherein said slot has an arcuate length from about 90* to about 270*.
 4. For use in a rotary valve including a casing defining a closure-receiving chamber having a main axis and having openings communicating with said chamber at spaced points to define a flowway therethrough disposed at an acute angle to said main axis, a closure member comprising: a. a body shaped to fit said chamber and having an axis of rotation coaxial with said chamber axis; b. a flow passage extending through opposite walls of said body generally at said acute angle with respect to said axis of rotation whereby to be in register with said openings at the full flowway-open position of said closure e member; c. each end of said passage defining an elongate slot extending circumferentially of said body and defined by convergent walls inclined inwardly of said body to intersect said passage parallel to the flow axis of said passage; d. said body having a non-slotted portion between the opposite ends of said slot defining a closure portion adapted to close off a flowway opening in the flowway-closing position of the closure member; and e. means carried by the ends of said body for journaling said body in said casing.
 5. A rotary valve, comprising: a. a casing defining a chamber having a main axis for receiving a flow-control member and having openings communicating with said chamber at spaced points to define a flowway therethrough on an axis disposed at an acute angle to said main axis of said chamber; and b. a flow-control member rotatably disposed in said chamber comprising: i. a tubular body shaped to fit said chamber and having an axis of rotation coaxial with said chamber axis and having one end in open communication with one of said openings; ii. a plurality of circumferentially spaced orifices eXtending through the wall of said body disposed generally in a plane normal to said axis of rotation and intermediate the ends of said body, each of said orifices having its axis at said acute angle whereby to be coaxial with said flowway when rotated into register with the other of said openings; c. means connected to said body and journaled in said casing for rotating said flow-control member; d. a cylindrical operating stem extending to the exterior of said casing; and e. a plug member carried by the inner end of said operating stem removably closing the adjacent end of said tubular body and secured thereto against relative rotation.
 6. A rotary valve according to claim 5 having annular seal means disposed to seal between said body and said casing about said other of said openings.
 7. A rotary valve according to claim 5 wherein an annular seal packing surrounds each of said orifices for sealing between said body and said casing about said other of said openings.
 8. A rotary valve according to claim 5 wherein at least some of said orifices differ in cross-sectional area from others of said orifices.
 9. A rotary valve according to claim 5 wherein said body has at least one imperforate portion between said orifices adapted when in registry with said other of said openings to close off said flowway.
 10. A rotary valve according to claim 5 wherein the bore of said other one of said openings has a cross-sectional area substantially equal to that of the largest of said orifices and less than that of said one opening.
 11. A rotary valve according to claim 5 including a tubular adapter removably positioned in the other of said openings, the inner end of said adapter being shaped to effectively form a flush portion of the interior wall of said chamber, said adapter having an axial passage therethrough whose cross-sectional area is substantially equal to that of the largest of said orifices.
 12. A rotary valve according to claim 5 wherein said casing has an end wall closing one end of said chamber and through which said one of said openings communicates with said chamber, and a bonnet member removably closing the other end of said chamber and having an opening for journaling said means for rotating said flow-control member.
 13. For use in a rotary valve a closure member comprising: a. a body having a central axis of rotation; b. a flow passage extending through said body at an acute angle with respect to said axis of rotation; c. at least one end of said passage defining an elongate slot extending circumferentially of said body and defined at least in part by convergent walls inclined inwardly of said body to intersect said passage parallel to the flow axis thereof; d. said body having an a nonslotted portion between the opposite ends of said slot defining a closure portion; and e. means carried by the ends of said body for supporting the same for rotation about said central axis.
 14. A closure member according to claim 13 wherein said body is tubular. 